The frozen shrimp is the prim supply source for the peeled shrimps, the shrimp dumplings and the shrimp balls; before preparing the aforesaid food, the shell of a shrimp has to be removed. Currently, the peeling work is done manually; such method of removing the shell not only affects the peeling speed and the yield, but also results in bacterial contamination and dirt contamination to jeopardize the freshment and quality of the peeled shrimps; finally, the shrimps might be rejected by a buyer; the rejection percentage once raised up to 28.1%; the supplier reputation would be harmed seriously. Recently, the society has been changed from the previous farm society, the cost of manpower has been raised considerably to cause a shortage in manpower; moreover, the shrimp peeling workers are subject to being injured by shrimp shell or being contaminated by shrimps. In order to improve the productivity and quality, and to reduce the contamination during peeling process, a shrimp peeling machinery has to be developed. Some conventional shrimp peeling machines have been disclosed, such as U.S. Pat. Nos. 3,975,797, 4,400,849, 5,108,342, and 5,120,265 etal.; all of the aforesaid peeling machines for shrimps have their drawbacks in one way or another, and therefore none of them has been used widely. As a result, the inventor has, by referring to the prior art of the kind, developed a shrimp peeling machinery, in which the drawbacks of the prior art have been improved.
No matter a frozen shrimp or a fresh shrimp would look like, after peeling process, a peeled shrimp as shown in FIG. 1, which includes a tail section, six-ring body section and a head section; shrimps are processed through a conventional roller-type shrimp peeling machinery would have a low yield with more or less fragmental shell therein. A shrimp peeling machinery usually includes a plurality of peeling rollers to remove the shell of a shrimp, such as U.S. Pat. Nos. 4,400,849, 5,108,342, and 5,120,265; however, the peeling result would be reduced in the event of the peeling rollers being too large or small; in other words, if the peeling rollers are too large or small, the yield will be low because of a low peeling efficiency. A large peeling structure can provide a stronger peeling force, but the tail section of a shrimp is susceptible to being cut off by such a machine; in other words, the possibility of cutting off the tail section of a shrimp is in proportion to the size of the peeling rollers. If the size of the peeling rollers is small, the peeling force will be reduced or too little to remove a shell; however, the percentage of the tail section to be cut off will be reduced, but the percentage of fragmental shell left in the peeled shrimp will be high; such fragmental shell problem has to be solved through manual operation. The size of shrimps has a close relation to the size of the peeling rollers on the upper and the lower rows of the rollers, and to the angle formed between the upper and the lower rows of the rollers. Generally, the rollers in the conventional shrimp peeling machinery have a larger contained angle between the upper and the lower rows of rollers; in other words, a normal upper row roller will be unable to remove the shrimp shell; to improve such problem, a swinging spring or the like is mounted between the upper and lower row rollers, such as shown in U.S. Pat. Nos. 4,400,849, and 5,120,265; unfortunately, the tail section and the ring part nearing the tail section are susceptible to being cut off to cause a lower yield.